In such machines the forming of the blisters in the preheated and therefore readily deformable carrier strip is generally done with the aid of a source of compressed air driving portions of that strip into suitably shaped cavities or recesses of an underlying die whose bottoms are vented to the atmosphere. The die, acting as a movable mold plate, may be periodically reciprocated toward and away from a fixed abutment plate having air channels aligned with these cavities. After the deformed strip leaves the die, and upon sufficient hardening of the blisters, the latter may be engaged by stationary guides as well as by one or more peripherally indented transport rollers for advancing the strip in a precisely controlled manner through the filling and sealing stations following the molding station. After the filled blisters have been hermetically sealed by the application of the cover strip, the resulting composite tape may be divided at a cutting station into packages of one or more blisters each. The sealing station may include one or more counterrollers coacting with one of the aforementioned transport rollers to laminate the cover strip to the underlying carrier strip, with or without the application of additional heat.
The size and shape of the blisters depend, of course, on the configuration of the goods to be packaged or, in the case of a liquid or paste, on the volume to be enclosed in each blister. Changing from one shape to another, aside from requiring the use of a different die in the molding station, generally necessitates also the replacement of the indented transport roller or rollers by others conforming to the new shape. Similarly, guide ribs disposed between the advancing blisters may have to be rearranged or exchanged.